Push primary term to replication tracker

This commit pushes the primary term into the replication tracker. This
is a precursor to using the primary term to resolving ordering problems
for retention leases. Namely, it can be that out-of-order retention
lease sync requests arrive on a replica. To resolve this, we need a
tuple of (primary term, version). For this to be, the primary term needs
to be accessible in the replication tracker. As the primary term is part
of the replication group anyway, this change conceptually makes sense.

server/src/main/java/org/elasticsearch/index/seqno/ReplicationTracker.java

@@ -33,6 +33,7 @@
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.shard.AbstractIndexShardComponent;
+import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.index.shard.ReplicationGroup;
 import org.elasticsearch.index.shard.ShardId;
 
@@ -92,6 +93,31 @@ public class ReplicationTracker extends AbstractIndexShardComponent implements L
      */
     volatile boolean primaryMode;
 
+    /**
+     * The current operation primary term. Management of this value is done through {@link IndexShard} and must only be done when safe. See
+     * {@link #setOperationPrimaryTerm(long)}.
+     */
+    private volatile long operationPrimaryTerm;
+
+    /**
+     * Returns the current operation primary term.
+     *
+     * @return the primary term
+     */
+    public long getOperationPrimaryTerm() {
+        return operationPrimaryTerm;
+    }
+
+    /**
+     * Sets the current operation primary term. This method should be invoked only when no other operations are possible on the shard. That
+     * is, either from the constructor of {@link IndexShard} or while holding all permits on the {@link IndexShard} instance.
+     *
+     * @param operationPrimaryTerm the new operation primary term
+     */
+    public void setOperationPrimaryTerm(final long operationPrimaryTerm) {
+        this.operationPrimaryTerm = operationPrimaryTerm;
+    }
+
     /**
      * Boolean flag that indicates if a relocation handoff is in progress. A handoff is started by calling {@link #startRelocationHandoff}
      * and is finished by either calling {@link #completeRelocationHandoff} or {@link #abortRelocationHandoff}, depending on whether the

server/src/main/java/org/elasticsearch/index/shard/IndexShard.java

@@ -199,7 +199,6 @@ public class IndexShard extends AbstractIndexShardComponent implements IndicesCl
     protected volatile ShardRouting shardRouting;
     protected volatile IndexShardState state;
     private volatile long pendingPrimaryTerm; // see JavaDocs for getPendingPrimaryTerm
-    private volatile long operationPrimaryTerm;
     protected final AtomicReference<Engine> currentEngineReference = new AtomicReference<>();
     final EngineFactory engineFactory;
 
@@ -308,7 +307,7 @@ public IndexShard(
         final String aId = shardRouting.allocationId().getId();
         this.globalCheckpointListeners =
                 new GlobalCheckpointListeners(shardId, threadPool.executor(ThreadPool.Names.LISTENER), threadPool.scheduler(), logger);
-        this.replicationTracker =
+        final ReplicationTracker replicationTracker =
                 new ReplicationTracker(
                         shardId,
                         aId,
@@ -317,6 +316,7 @@ public IndexShard(
                         globalCheckpointListeners::globalCheckpointUpdated,
                         threadPool::absoluteTimeInMillis,
                         retentionLeaseSyncer);
+        this.replicationTracker = replicationTracker;
 
         // the query cache is a node-level thing, however we want the most popular filters
         // to be computed on a per-shard basis
@@ -336,8 +336,9 @@ public boolean shouldCache(Query query) {
         }
         indexShardOperationPermits = new IndexShardOperationPermits(shardId, threadPool);
         searcherWrapper = indexSearcherWrapper;
-        pendingPrimaryTerm = indexSettings.getIndexMetaData().primaryTerm(shardId.id());
-        operationPrimaryTerm = pendingPrimaryTerm;
+        final long primaryTerm = indexSettings.getIndexMetaData().primaryTerm(shardId.id());
+        this.pendingPrimaryTerm = primaryTerm;
+        replicationTracker.setOperationPrimaryTerm(primaryTerm);
         refreshListeners = buildRefreshListeners();
         lastSearcherAccess.set(threadPool.relativeTimeInMillis());
         persistMetadata(path, indexSettings, shardRouting, null, logger);
@@ -399,7 +400,7 @@ public long getPendingPrimaryTerm() {
 
     /** Returns the primary term that is currently being used to assign to operations */
     public long getOperationPrimaryTerm() {
-        return this.operationPrimaryTerm;
+        return replicationTracker.getOperationPrimaryTerm();
     }
 
     /**
@@ -508,7 +509,7 @@ public void updateShardState(final ShardRouting newRouting,
                             assert pendingPrimaryTerm == newPrimaryTerm :
                                 "shard term changed on primary. expected [" + newPrimaryTerm + "] but was [" + pendingPrimaryTerm + "]" +
                                 ", current routing: " + currentRouting + ", new routing: " + newRouting;
-                            assert operationPrimaryTerm == newPrimaryTerm;
+                            assert getOperationPrimaryTerm() == newPrimaryTerm;
                             try {
                                 replicationTracker.activatePrimaryMode(getLocalCheckpoint());
                                 /*
@@ -704,23 +705,23 @@ public Engine.IndexResult applyIndexOperationOnPrimary(long version, VersionType
                                                            boolean isRetry)
         throws IOException {
         assert versionType.validateVersionForWrites(version);
-        return applyIndexOperation(getEngine(), UNASSIGNED_SEQ_NO, operationPrimaryTerm, version, versionType, ifSeqNo,
+        return applyIndexOperation(getEngine(), UNASSIGNED_SEQ_NO, getOperationPrimaryTerm(), version, versionType, ifSeqNo,
             ifPrimaryTerm, autoGeneratedTimestamp, isRetry, Engine.Operation.Origin.PRIMARY, sourceToParse);
     }
 
     public Engine.IndexResult applyIndexOperationOnReplica(long seqNo, long version, long autoGeneratedTimeStamp,
                                                            boolean isRetry, SourceToParse sourceToParse)
         throws IOException {
-        return applyIndexOperation(getEngine(), seqNo, operationPrimaryTerm, version, null, UNASSIGNED_SEQ_NO, 0,
+        return applyIndexOperation(getEngine(), seqNo, getOperationPrimaryTerm(), version, null, UNASSIGNED_SEQ_NO, 0,
             autoGeneratedTimeStamp, isRetry, Engine.Operation.Origin.REPLICA, sourceToParse);
     }
 
     private Engine.IndexResult applyIndexOperation(Engine engine, long seqNo, long opPrimaryTerm, long version,
                                                    @Nullable VersionType versionType, long ifSeqNo, long ifPrimaryTerm,
                                                    long autoGeneratedTimeStamp, boolean isRetry, Engine.Operation.Origin origin,
                                                    SourceToParse sourceToParse) throws IOException {
-        assert opPrimaryTerm <= this.operationPrimaryTerm: "op term [ " + opPrimaryTerm + " ] > shard term [" + this.operationPrimaryTerm
-            + "]";
+        assert opPrimaryTerm <= getOperationPrimaryTerm()
+                : "op term [ " + opPrimaryTerm + " ] > shard term [" + getOperationPrimaryTerm() + "]";
         ensureWriteAllowed(origin);
         Engine.Index operation;
         try {
@@ -783,13 +784,13 @@ private Engine.IndexResult index(Engine engine, Engine.Index index) throws IOExc
     }
 
     public Engine.NoOpResult markSeqNoAsNoop(long seqNo, String reason) throws IOException {
-        return markSeqNoAsNoop(getEngine(), seqNo, operationPrimaryTerm, reason, Engine.Operation.Origin.REPLICA);
+        return markSeqNoAsNoop(getEngine(), seqNo, getOperationPrimaryTerm(), reason, Engine.Operation.Origin.REPLICA);
     }
 
     private Engine.NoOpResult markSeqNoAsNoop(Engine engine, long seqNo, long opPrimaryTerm, String reason,
                                               Engine.Operation.Origin origin) throws IOException {
-        assert opPrimaryTerm <= this.operationPrimaryTerm : "op term [ " + opPrimaryTerm + " ] > shard term [" + this.operationPrimaryTerm
-            + "]";
+        assert opPrimaryTerm <= getOperationPrimaryTerm()
+                : "op term [ " + opPrimaryTerm + " ] > shard term [" + getOperationPrimaryTerm() + "]";
         long startTime = System.nanoTime();
         ensureWriteAllowed(origin);
         final Engine.NoOp noOp = new Engine.NoOp(seqNo, opPrimaryTerm, origin, startTime, reason);
@@ -805,31 +806,31 @@ private Engine.NoOpResult noOp(Engine engine, Engine.NoOp noOp) {
     }
 
     public Engine.IndexResult getFailedIndexResult(Exception e, long version) {
-        return new Engine.IndexResult(e, version, operationPrimaryTerm);
+        return new Engine.IndexResult(e, version, getOperationPrimaryTerm());
     }
 
     public Engine.DeleteResult getFailedDeleteResult(Exception e, long version) {
-        return new Engine.DeleteResult(e, version, operationPrimaryTerm);
+        return new Engine.DeleteResult(e, version, getOperationPrimaryTerm());
     }
 
     public Engine.DeleteResult applyDeleteOperationOnPrimary(long version, String type, String id, VersionType versionType,
                                                              long ifSeqNo, long ifPrimaryTerm)
         throws IOException {
         assert versionType.validateVersionForWrites(version);
-        return applyDeleteOperation(getEngine(), UNASSIGNED_SEQ_NO, operationPrimaryTerm, version, type, id, versionType,
+        return applyDeleteOperation(getEngine(), UNASSIGNED_SEQ_NO, getOperationPrimaryTerm(), version, type, id, versionType,
             ifSeqNo, ifPrimaryTerm, Engine.Operation.Origin.PRIMARY);
     }
 
     public Engine.DeleteResult applyDeleteOperationOnReplica(long seqNo, long version, String type, String id) throws IOException {
         return applyDeleteOperation(
-            getEngine(), seqNo, operationPrimaryTerm, version, type, id, null, UNASSIGNED_SEQ_NO, 0, Engine.Operation.Origin.REPLICA);
+            getEngine(), seqNo, getOperationPrimaryTerm(), version, type, id, null, UNASSIGNED_SEQ_NO, 0, Engine.Operation.Origin.REPLICA);
     }
 
     private Engine.DeleteResult applyDeleteOperation(Engine engine, long seqNo, long opPrimaryTerm, long version, String type, String id,
                                                      @Nullable VersionType versionType, long ifSeqNo, long ifPrimaryTerm,
                                                      Engine.Operation.Origin origin) throws IOException {
-        assert opPrimaryTerm <= this.operationPrimaryTerm : "op term [ " + opPrimaryTerm + " ] > shard term [" + this.operationPrimaryTerm
-            + "]";
+        assert opPrimaryTerm <= getOperationPrimaryTerm()
+                : "op term [ " + opPrimaryTerm + " ] > shard term [" + getOperationPrimaryTerm() + "]";
         ensureWriteAllowed(origin);
         // When there is a single type, the unique identifier is only composed of the _id,
         // so there is no way to differentiate foo#1 from bar#1. This is especially an issue
@@ -845,7 +846,7 @@ private Engine.DeleteResult applyDeleteOperation(Engine engine, long seqNo, long
                 return new Engine.DeleteResult(update);
             }
         } catch (MapperParsingException | IllegalArgumentException | TypeMissingException e) {
-            return new Engine.DeleteResult(e, version, operationPrimaryTerm, seqNo, false);
+            return new Engine.DeleteResult(e, version, getOperationPrimaryTerm(), seqNo, false);
         }
         if (mapperService.resolveDocumentType(type).equals(mapperService.documentMapper().type()) == false) {
             // We should never get there due to the fact that we generate mapping updates on deletes,
@@ -1272,7 +1273,7 @@ public void prepareForIndexRecovery() {
     }
 
     public void trimOperationOfPreviousPrimaryTerms(long aboveSeqNo) {
-        getEngine().trimOperationsFromTranslog(operationPrimaryTerm, aboveSeqNo);
+        getEngine().trimOperationsFromTranslog(getOperationPrimaryTerm(), aboveSeqNo);
     }
 
     /**
@@ -2382,7 +2383,7 @@ private EngineConfig newEngineConfig() {
                 Collections.singletonList(refreshListeners),
                 Collections.singletonList(new RefreshMetricUpdater(refreshMetric)),
                 indexSort, circuitBreakerService, replicationTracker, replicationTracker::getRetentionLeases,
-                () -> operationPrimaryTerm, tombstoneDocSupplier());
+                () -> getOperationPrimaryTerm(), tombstoneDocSupplier());
     }
 
     /**
@@ -2462,7 +2463,7 @@ private <E extends Exception> void bumpPrimaryTerm(final long newPrimaryTerm,
                                                        @Nullable ActionListener<Releasable> combineWithAction) {
         assert Thread.holdsLock(mutex);
         assert newPrimaryTerm > pendingPrimaryTerm || (newPrimaryTerm >= pendingPrimaryTerm && combineWithAction != null);
-        assert operationPrimaryTerm <= pendingPrimaryTerm;
+        assert getOperationPrimaryTerm() <= pendingPrimaryTerm;
         final CountDownLatch termUpdated = new CountDownLatch(1);
         asyncBlockOperations(new ActionListener<Releasable>() {
             @Override
@@ -2488,12 +2489,12 @@ private void innerFail(final Exception e) {
             public void onResponse(final Releasable releasable) {
                 final RunOnce releaseOnce = new RunOnce(releasable::close);
                 try {
-                    assert operationPrimaryTerm <= pendingPrimaryTerm;
+                    assert getOperationPrimaryTerm() <= pendingPrimaryTerm;
                     termUpdated.await();
                     // indexShardOperationPermits doesn't guarantee that async submissions are executed
                     // in the order submitted. We need to guard against another term bump
-                    if (operationPrimaryTerm < newPrimaryTerm) {
-                        operationPrimaryTerm = newPrimaryTerm;
+                    if (getOperationPrimaryTerm() < newPrimaryTerm) {
+                        replicationTracker.setOperationPrimaryTerm(newPrimaryTerm);
                         onBlocked.run();
                     }
                 } catch (final Exception e) {
@@ -2579,14 +2580,14 @@ private void innerAcquireReplicaOperationPermit(final long opPrimaryTerm,
         final ActionListener<Releasable> operationListener = new ActionListener<Releasable>() {
             @Override
             public void onResponse(final Releasable releasable) {
-                if (opPrimaryTerm < operationPrimaryTerm) {
+                if (opPrimaryTerm < getOperationPrimaryTerm()) {
                     releasable.close();
                     final String message = String.format(
                         Locale.ROOT,
                         "%s operation primary term [%d] is too old (current [%d])",
                         shardId,
                         opPrimaryTerm,
-                        operationPrimaryTerm);
+                        getOperationPrimaryTerm());
                     onPermitAcquired.onFailure(new IllegalStateException(message));
                 } else {
                     assert assertReplicationTarget();
@@ -2647,7 +2648,7 @@ public void onFailure(final Exception e) {
     }
 
     private boolean requirePrimaryTermUpdate(final long opPrimaryTerm, final boolean allPermits) {
-        return (opPrimaryTerm > pendingPrimaryTerm) || (allPermits && opPrimaryTerm > operationPrimaryTerm);
+        return (opPrimaryTerm > pendingPrimaryTerm) || (allPermits && opPrimaryTerm > getOperationPrimaryTerm());
     }
 
     public int getActiveOperationsCount() {